Rotary head for gr



(No Model.)

T. L. STURTEVANT.

ROTARY HEAD FOR GRINDING MILLS. No. 324,047. Patented Aug. 11, 1885.

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U a C a 7152 11601960. A A fizz/6222 0;. 76g

N. PETERS, Phclo-Lthogmphur. Washmgiun. n. c.

UNITED STATES PATEN T OTTTQ THOMAS LEGGETT STURTEVANT, OF FRAMINGHAM, ASSIGNOR TO THE STUltTEVANT MILL COMPANY, OF BOSTON, MASSACHUSETTS.

ROTARY HEAD FOR GRlNDlNG-MiLLS.

SPECIFICATION forming part of Letters Patent No. 324,0d7, dated August 11, 1885.

Application filed April 16, 1885.

To all whom it may concern.-

Be it known that I, THOMAS LEGGETI SIURTEVAN'I, a citizen of the United States, residing at Framingham,in the county of Middlesex and State of Massachusetts, have invented certain new and useful Improvements in Rotary Heads for Grinding-lllills; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled inthe art to which it appertains to make and use the same, reference being had to the accompanying drawings, and to letters or figures of reference marked thereon, which i'orm a part of this specification.

This invention relates to grinding or attrition mills, so called, by which hard materials, especially phosphates, quartz, or other analogous substances, may be broken and reduced to a fine comminuted mass. My present improvements consist in the construction and combination of parts more fully hereinafter described and claimed, by which the steel bushing forming part of the rotary-head is secured and held in place, and at the same time the end'of the shaft rotating such head is protected and prevented from being worn by the action of material in process of grinding.

The drawings accompanying this specification represent, in Figure 1, a central partly sectional elevation of a mill embodying my improvements. Fig. 2 is an enlarged vertical section of the rotary head, and Fig. 3 a 'simi lar view containing modifications. Fig. at is a section of the clamping-ring.

The improvements herein described relate especially to that class of grinding or attrition mills in which the material is reduced by the frictional contact with each other of the various particles or lumps composing such material. A notable instance of this class of mills is described in Letters Patent No. 255,550, issued to myself on the 28th day of March, 1882.

In the drawings the casing of the mill is shown at A, as provided with similarly-dis posed oppositely rotating heads B B, driven by the shafts O O, which are properly mounted in suitable bearings.

Hitherto I have found difficulty in securing to the heads B B the bushings D .I). These (No model.)

bushings are made separate from the heads to which they are attached in order that said bushings may the more easily and readily be replaced with new ones when \Vorn out or broken.

To prevent the material from escaping between the rotary heads and their casing A, I have disposed packing-rings O, which contain the packing a, the rings being secured to the casing by a series of buttons or their equivalents and capable of adjustment upon and about the bushings 1) D.

Generally the retaining screws or bolts have been inserted radially of the heads B B, but I find they are continually working loose. I, therefore, in the present case have disposed them parallel with the shafts (J 0, but concentrically around them with the heads of said bolts projecting interiorly.

Each bushing or ring D, forming the receptacle of the rotary head, and in which the material is maintained when the mill is in active operation, is to be formed of steel, gunmetal, or some tough, hard metallic substance, circular in shape, with its greatest external diameter equal to the rotary head to which it is secured. This ring or bushing may be contracted or reduced in diameter the distance overlapped by the rotary head, and thus a shoulder, a, is formed, against which the ring rests for a bearing. The interior of the bushing may be divided by partitions variously shaped, or lugs may be cast of ditterentshapes; as found convenient or useful, and as has been partly described in Letters Patent No. 255,550, issued to me on the 28th day of March, 1882, or as has been accomplished by myself heretofore in the interior of head-casings.

At the back end of the ring or bushing is formed an interiorly-projecting annular ring or shoulder, 11, against which a circular clamping-plate, E, abuts, (see Fig. 2,) and by means of which said ring is maintained in place. The plate E is afi xed to the'rotary head by means of the bolts 0 c, &c., engaging in the latter.

I have found in operating the mill that the ends (I d of the driving-shafts G 0 have also become worn and damaged by contact with the material in process of grinding, as also the back parts of the heads, owing to the rotary heads and shai'ts being uncovered. In the present instance I obviate this ditliculty by driving the head I; well upon its shaft 0, and thus give the head a firm bearing, while the shaft may be allowed to project slightly within the head, as shown. Furthermore, to protect the latter .I have cast a cap, Gr, made of the same metal as the ring or bushing D. This cap is in general shape like a hat, (see Fig. 3,) or may be that of a frustum ot' a cone, as in Fig. 2, and is provided with a recess or chamher, 0, arranged to fit the projecting end of the shaft. Moreover, the circular plate E is centrall y bored and tapered, as shown at f, in order that the two surfaces of the plate and the cap shall not only coincide one with the other and form atight tit, but thattheeitect of tightening thebolts 00 upon the plate E shall force the latter down upon the cap, the action of the two inclined faces upon each other acting as a double wedge to lock all the parts rigidly together.

In Fig. 3 l have shown a modification ofthe construction and arrangement of parts represented in Fig. 2. From the construction of the bushing l), which is provided with interior lugs, 5 g, &c., thedisposition oisaid lugs would prevent the introduction of an integral or entire clamping-plate, as shown in Fig. 2. I have therefore constructed an annular clamping-ring, E, of two parts, as shown in Fig. 4, the line of division being in the plane 00 00. I thus make a scart'joint and introduce the two parts separately, and by means of the bolts secure the parts rigidly together. In said F i 3 it will be further noticed that the shaft-cap G is somewhat modified in form, and is socured in place by means ofthe clamping-ringE. The following description will show how simply and easily a new bushing, 1), is secured in the rotary head: First, the bushingisplaced in its proper position within the head; then the cap G is inserted upon the end of its shaft C, and, finally, the clamping-plate E is disposed in its proper position, with the inclined face of said cap coinciding with the similarly-beveled bore j of the plate It. The bolts 0 c are then screwed up tightly, and the ring I), the sha'ltcap G, and clam pin g-plate E are united firmly and rigidly to the rotary head I3. \Vhen the clamping-plate E is in position upon the cap, the interior surfaces, against which the material rests, are flush with each other. Thus a rotary head is formed which is inexpensive, strong, and not liable to break or get out ot order. liurthermore, any one part may be easily replaced in case it becomes worn or broken without the expense attendant upon the construction of an entire new head, which would be necessary in case it was formed of one casting. Furthermore, the cap completely protects the end of the shaft, while the clampin gplate and the bushing protect the rotary head proper. Any one of these three parts, it will be readily understood, may be replaced in case of wear with but a very few minutes delay or cessation in the active operation of the grinding-mill.

I claim-- 1. In an attrition-mill, the combination, with a rotary shaft and its head, of the bushing partially inclosed by the head, and a clampingplate, substantially as herein described.

2. In an attrition-mill, thecombination, with the rotary head and its shaft, of the cap covering and clamping plate, substantially as set forth.

3. In an attritionmill, the combination, with the bushing D, interiorly provided with the lugs or partitions g g, of the rotary head 13, partially inclosin g said bushing, and to which the latter is secured, the cap covering, and the clamping plate, substantially as stated.

In testimony whereof I atiix my signature in presence of two witnesses.

THOMAS LEGGETT SlUll'lEVAN'l.

XVitnesses:

H. E. LODGE, A. F. HAYDEN. 

